$2-7.($Real interest rates: approximation method$)$ You are considering investing money in Treasury bills and wondering what the real risk$-$free rate of interest is$.$ Currently, Treasury bills are yielding $4\mathrm{.}5\%$ and the future inflation rate is expected to be $2\mathrm{.}1\%$ per year. Ignoring the cross product between the real rate of interest and the inflation rate, what is the real risk$-$free rate of interest?